If $x \bigtriangleup y = 5x+y$ and $x \boxdot y = 4x^{2}+y^{2}$, find $(1 \bigtriangleup -4) \boxdot 2$.
Answer: First, find $1 \bigtriangleup -4$ $ 1 \bigtriangleup -4 = (5)(1)-4$ $ \hphantom{1 \bigtriangleup -4} = 1$ Now, find $1 \boxdot 2$ $ 1 \boxdot 2 = 4(1^{2})+2^{2}$ $ \hphantom{1 \boxdot 2} = 8$.